ABS Guide for Offshore Racing Yachts

[Younglad]

Toward the end of Section 7.3.2 in the ABS Guide for Offshore Racing Yachts there is a formula for the minimum buckling stress of the skins. The formula appears in a paragraph relating to honeycomb cores, but does not expressly apply only when such cores are used. Does the formula apply only to honeycomb cores?
In the discussion of the ABS rule in the Principals of Yacht Design, Larsson and Eliasson don't mention this formula.

I would have thought that the paragraph about honeycomb cores is stand alone. As far as I'm understand it, the formula for buckling stress is for any sandwich construction, in the context it's given, the section ending "...will be given special considerations" does in fact end there, and is only a specific note.

I do however stand to be corrected....

[Younglad]

I'm inclined to agree based on normal sentence construction and logic. The problem I am having, however, is that the formula requires that skin buckling stress must equal compressive strength. Very often compressive strength is not the controlling factor in designing a laminate. Sometimes compressive strength is 3x that theoritically required because another factor is controlling. When this happens, it seems buckling stress is required to be excessively high as well. The problem can be solved by artificially lowering compressive strength (add resin or mat), but this seems crazy. Making the laminate thicker may not be all bad, but why should making the laminate thicker by adding mat (low compressive str.) be good, and making it thicker with roving (same strength) be bad. I could calculate a theoritical minimum compresive strength, holding all other variables the same, but this doesn't seem to be what the formula requires..., or does it?